For example, a vane pump including a rotor configured to receive motive power, or an internal gear pump is used as an oil pump for supplying hydraulic oil to fluid devices mounted in an automobile, such as a hydraulic motive power steering system and a hydraulic continuously variable transmission (Japanese Patent Publication No. 2014-17790 and Japanese Patent Publication No. 2011-106543A).
In an automobile provided with a control device configured to stop the engine under a predetermined stop condition, and to start the engine under a predetermined start condition, e.g. when the accelerator pedal is pressed, an oil pump is driven by an electric motor while the engine is not operating.
The oil pump driving device disclosed in Japanese Patent Publication No. 2011-106543A (hereinafter the JP ′543 patent) includes a single oil pump; a path through which the motive power output from the engine is transmitted to the oil pump; and a path through which the motive power output from the electric motor is transmitted to the oil pump. These paths each include a one-way clutch configured to selectively permit and stop the transmission of motive power to the oil pump. These one-way clutches are both configured to be locked/engaged when motive power in the same one direction is applied thereto (so as to transmit the motive power). Such an oil pump driving device is therefore configured such that the single oil pump can be driven by either of the engine and the electric motor.
In the oil pump driving device of the JP ′543 patent, since the two one-way clutches are disposed on the respective sides of the oil pump, the entire axial length of the housing in which these components are received is large. It is thus difficult to mount this oil pump driving device to the engine or the transmission.
In view of the above background, it is an object of the present invention to provide an oil pump driving device which includes a single oil pump capable of being driven by either of the engine and the electric motor, and which is short in entire axial length.